Comparison of the energy dependence of near-barrier He6 and He8+Pb208 optical potentials

N. Keeley, K. W. Kemper, I. Martel, K. Rusek, and A. M. Sánchez-Benítez
Phys. Rev. C 99, 024603 – Published 1 February 2019

Abstract

Optical model analyses of recent He8+Pb208 elastic scattering data for incident energies of 16 and 22 MeV, together with existing data for He6+Pb208 at the same energies, reveal a significant difference in the behavior of the imaginary part of the optical potential for the two isotopes as the incident energy is reduced below the Coulomb barrier. While the strength of the He6 imaginary potential reduces as the incident energy is reduced below the barrier, as is the case for most heavy ions, that for He8 remains constant within uncertainties and may even increase. Similar behavior was observed for the Li6 and Li7+Pb208 optical potentials [Nucl. Phys. A 571, 326 (1994)], with the strength of the Li6 imaginary potential appearing to increase as the incident energy is reduced below the Coulomb barrier while that for Li7 reduces. However, the explanation for this difference in behavior put forward in that work, viz. the increased importance of breakup for Li6 as the incident energy is reduced towards the Coulomb barrier, later supported explicitly by calculations [Phys. Lett. B 427, 1 (1998)], does not hold for the He isotopes since it is the He8 optical potential that behaves in a similar fashion to that of Li6 in spite of He8 having the higher breakup threshold of the two He isotopes. We conclude that the difference is due to the influence of 3n and 4n stripping on the He8 scattering, reactions which cannot take place for He6 projectiles.

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  • Received 1 October 2018
  • Revised 18 December 2018

DOI:https://doi.org/10.1103/PhysRevC.99.024603

©2019 American Physical Society

Physics Subject Headings (PhySH)

Nuclear Physics

Authors & Affiliations

N. Keeley1,*, K. W. Kemper2,3, I. Martel4, K. Rusek3, and A. M. Sánchez-Benítez5

  • 1National Centre for Nuclear Research, ul. Andrzeja Sołtana 7, 05-400 Otwock, Poland
  • 2Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
  • 3Heavy Ion Laboratory, University of Warsaw, ul. Pasteura 5a, 02-093 Warsaw, Poland
  • 4Science and Technology Research Centre (STRC), University of Huelva, 21071 Huelva, Spain
  • 5Departamento de Ciencias Integradas y Centro de Estudios Avanzados en Física, Matemáticas y Computación, Facultad de Ciencias Experimentales, Universidad de Huelva, 21071 Huelva, Spain

  • *nicholas.keeley@ncbj.gov.pl

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Vol. 99, Iss. 2 — February 2019

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